Jet Streaks ?

What do you look for in finding a jet streak on the 200/250 mb upper air map ? Is it the portion of the jet stream that's 50 kts or greater or is there more to it then that ? Thanks for any helpfull info.

Jon Miller
I just look for an area of higher winds embedded within the general jet stream, not a specific value. If there is a generally broad area of 100knt winds at whatever height, and there is an embedded area of 130knts, that would be a jet streak... I generally consider it a "streak" if it's more than 100 miles long and 50 miles wide. Anything smaller than that, and I consider a jet maximum/local jet max.